here, the big argument is an uint256_t (https://github.com/libbitcoin/libbitcoin/blob/version3/src/chain/compact.cpp#L159)
and we're doing static_cast<uint64_t>(big) .
and that gives a crash and burn.
if you have any thoughts on this one let me know.
now, going forward, we may just end up with attempting to use GCC 6 and LibBoost 1.66.0, as we have that at hand.
